Continued frustration with parameters : jump to report

I have one report (R1) which includes a list of ports ("=Fields!Port_Name.Value")

Another report (R2) supplies details for individual reports and has a parameter named PortDWIDPortName which gets port names from the same dimension as those in R1. So in the field properties of the Port field in R1, I selected Navigation > Jump To Report and entered PortDWIDPortName = Fields!Port_Name.Value (also tried changing .Value to .Key or .UniqueName) but although it jumps to report R2 it does not enter a value for the parameter (ie leaves it blank or displays <Select Value> depending on whether multivalue or not).

Does anyone know the right syntax to pass the parameter ? If not, does anyone know to view what Jump To Parameter is returning so I can figure how to doctor it!

Thanks

I can't believe it I think I have the answer : it is ="[Port DWID].[Port Name].&[" & Fields!Port_Name.Value & "]"

Well that was kind of intuitive ... not!!

Richard